Accession Number : AD0919326

Title :   A Study of Properties and Behavior of High Temperature Gas Turbine Materials.

Descriptive Note : Final rept. 31 May 73-31 Mar 74,

Corporate Author : STANFORD RESEARCH INST MENLO PARK CA

Personal Author(s) : Sedlacek, Rudolf ; Jones, Robin L.

Report Date : MAR 1974

Pagination or Media Count : 56

Abstract : Expanded-ring tests were performed in 30 to 35% relative humidity air at 70 + or - 2 F on specimens machined from two tiles of Norton HS-130 hot-pressed silicon nitride. No statistically significant variation of mean fracture strength could be detected for groups of specimens tested at stress rates between 150 psi/sec and 500,000 psi/sec. The mean fracture strength was also found to be independent of original specimen location in the tile. A significant difference in the mean fracture strengths of the two tiles was detected and was attributed to differences in the extreme-value volume distributions of flaw sizes. The fracture strength data for specimens from both tiles showed an excellent fit with single-valued two-parameter Weibull distributions. Values of the Weibull modulus for the two tiles were 9.67 and 11.01. The range of flaw sizes required to account for the fracture strength data was estimated from linear elastic fracture mechanics theory, and the existence of flaws with sizes within the estimated range was confirmed by scanning-electron fractography. (Author)

Descriptors :   (*SILICON NITRIDES, GAS TURBINES), (*TURBINE STATORS, SILICON NITRIDES), (*ROTORS, SILICON NITRIDES), (*GAS TURBINES, MATERIALS), TILES, MECHANICAL PROPERTIES, TENSILE PROPERTIES, DEFECTS(MATERIALS), FRACTURE(MECHANICS), HIGH PRESSURE, ELECTRONIC SCANNERS, FRACTOGRAPHY, SIZES(DIMENSIONS), DISTRIBUTION, STRESSES, STATISTICAL ANALYSIS, EQUATIONS, MATHEMATICAL MODELS, HOT PRESSING.

Subject Categories : Ceramics, Refractories and Glass
      Jet and Gas Turbine Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE